Magnetic Tracker Dual-Frequency Pose Determination
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Solution Overview
Problem
Magnetic tracking systems for hand-held input devices in electronic devices like augmented reality computing and gaming consoles face limitations due to the 1/r^3 fall-off of magnetic fields, leading to signal strength issues that require power adjustments, causing temporary loss of pose measurement and potential saturation, which complicates control software and introduces performance problems.
Innovation Solution
A system that transmits multiple magnetic fields of different frequencies and power levels, allowing the receiver to select the field with the best signal-to-noise ratio without power adjustments, enabling continuous pose determination over a wider range by using a combination of fields with overlapping acceptable signal ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single magnetic field frequency is used, then the system is simpler to implement, but the useful range is limited due to signal saturation at close distances and signal weakness at far distances
Solution Approach 1:
The magnetic tracking system segments the operating range by using multiple magnetic field frequencies (e.g., first frequency and second frequency), where each frequency is optimized for specific distance ranges. This allows the receiver to select the appropriate frequency based on the current separation distance, thereby extending the overall useful range while maintaining system manageability through modular frequency handling.
Solution Approach 2:
The system changes the frequency parameter of the magnetic field to adapt to different operating conditions. By transmitting magnetic fields at multiple frequencies and allowing the receiver to select the optimal frequency based on signal quality and distance, the system dynamically adjusts its operating parameters to maintain performance across a wider range of separation distances.
2Measurement precision
If power level adjustments are made to maintain signal strength, then the signal-to-noise ratio is improved, but temporary loss of pose measurement occurs and control software becomes more complex
Solution Approach 1:
The system performs preliminary action by pre-configuring multiple magnetic field frequencies with different characteristics before operation. The receiver is pre-programmed with the ability to recognize and evaluate signals at these different frequencies, allowing it to autonomously select the optimal frequency without requiring complex real-time power adjustments or communication protocols, thus maintaining measurement continuity.
Solution Approach 2:
The receiver performs self-service by autonomously evaluating the quality of magnetic field signals at different frequencies and automatically selecting the frequency with the best signal-to-noise ratio. This eliminates the need for complex external control software to manage power adjustments, as the system self-regulates based on real-time signal conditions, preventing temporary loss of pose measurement.
3Length of stationary object
If high power is used to extend range, then the useful distance is increased, but signal saturation occurs at close distances
Solution Approach 1:
The system applies local quality by assigning different magnetic field frequencies to different distance ranges. A first frequency is optimized for greater separation distances where higher range is needed, while a second frequency is optimized for lesser separations where lower power is required to avoid saturation. The receiver selects the appropriate frequency based on the local operating condition, thus extending the useful range without causing signal saturation at close distances.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for precise and continuous determination of the relative pose between devices, improving system performance and range without introducing delays or gaps in measurement, by selecting the optimal frequency based on signal quality.
Implementation Method 1
a transmitting device transmits multiple magnetic fields of different frequencies, including a first magnetic field with a higher power level and a second field with a lower power level
Data Source
AI summary
A system of a transmitter and a receiver uses magnetic fields to determine the relative position and orientation, or pose, of the two devices. For example, the transmitter could be a handheld control device and the receiver could be an augmented reality or other computing solution. The transmitter transmits two magnetic fields of differing frequencies and differing amplitudes. The receiver selects the one of the magnetic fields with the higher signal to noise ratio to determine the relative pose of the transmitter. By using two magnetic fields of different amplitudes, the pose can be determined over a wider range of separations.